Heat the oven to 400°F/200°C.
Line a baking sheet with parchment paper and lightly brush with olive oil.
In a large bowl, combine the chicken, spinach, breadcrumbs, egg, shallot, mustard, garlic powder, salt, and pepper. Mix gently until just combined.
Shape the mixture into 6 even patties. Arrange on the prepared baking sheet and drizzle with olive oil.
Bake until the burgers are cooked through and lightly browned, about 18 minutes, flipping halfway through.
Broil for 1 to 2 minutes, until the tops are golden.
Serve with salad, buns, or your favorite toppings. Finish with lemon or lime juice.